Are maternal diabetes and preeclampsia independent simulators of fetal erythropoietin production?

Antepartum fetal surveillance and timing of delivery in the pregnancy complicated by diabetes mellitus

Pregnancies complicated by diabetes mellitus are associated with an increased risk of fetal and neonatal risks compared with pregnancies in the healthy gravida. Data suggest that stillbirth and perinatal mortality may be increased as much as 5 times for patients with insulin-dependent diabetes than in the general population. Pregnancies complicated by preexisting diabetes should undergo twice weekly surveillance with nonstress test or biophysical profile or a combination of both. Doppler studies should be reserved for those patients with vascular disease, intrauterine growth restriction, or hypertensive disorders.

Erythropoietin concentration among patients with and without preeclampsia

PURPOSE

Controversy exists in the literature regarding the association between erythropoietin levels and preeclampsia. This study was aimed to compare serum erythropoietin concentrations among patients with and without preeclampsia.

MATERIAL AND METHODS

A prospective study was designed and two groups were defined: 22 patients with preeclampsia (study group) and 19 normotensive patients (control group). Preeclampsia was defined as blood pressure higher than 140 mmHg systolic or 90 mmHg diastolic and proteinuria > 300/24 h or dipstick > 1. Women in the control group were matched for gestational age. Blood was collected in tubes containing EDTA, and centrifuged in 4 degrees C within 30 min of collection. Serum erythropoietin level was determined by ELISA (R&D Systems, Inc. Minneapolis, USA). Statistical analysis was performed using the SPSS package.

RESULTS

Erythropoietin concentration was higher among patients with preeclampsia, but did not reach significance (24.8 +/- 8.9 mU/ml vs. 19.9 +/- 9.9 mU/ml; P-0.19). Also, hemoglobin and hematocrit levels were similar in both groups (12.0 +/- 4.2 g/dl vs. 11.6 +/- 3.9 g/dl; P-0.16 and 36.5 +/- 10.8% vs. 35.3 +/- 11.4%; P-0.13, respectively).

CONCLUSIONS

A nonsignificant trend towards higher maternal serum levels of erythropoietin was demonstrated among patients with preeclampsia. Further prospective studies are needed to investigate the association between preeclampsia and erythropoietin.

The placenta at high altitude

The influence of oxygen pressure on placental and villous vascular development is reviewed and considered relative to the natural experiment afforded by residence at high altitude. Data obtained from normal high altitude pregnancies are compared with those from IUGR and preeclampsia, conditions believed to be caused by placental hypoxia. High altitude placentas are characterized by increased villous vascularization, thinning of the villous membranes, proliferation of the villous cytotrophoblast, and reduced perisyncytial fibrin deposition relative to low altitude placentas. The significance of reduced fibrin deposition is unknown; it could be explained by less apoptosis along the barrier membrane, less syncytiotrophoblast turnover, or altered ratios of local proversus anticoagulant production. Increased villous capillary density and thinning of the villous membranes increases oxygen diffusion capacity and is generally considered a beneficial adaptation. Nonetheless, there is evidence that hypoxia and/or reduced blood flow reduce placental nutrient transporter densities, and this may act in additive or synergistic fashion to reduce birth weight at high altitude. The available literature on high altitude placentas derives from less than 100 pregnancies from three different continents and six different ethnic groups, and were acquired in pregnancies ranging from 2500 to 4300 m in altitude. Thus differences between studies are likely to be due to variation in altitude and/or to ethnic variation, which in turn may be due to differences in population history of residence at high altitude (e.g., Andeans vs. Europeans). Nonetheless, systematic examination of human placental development under conditions of lowered maternal arterial oxygen pressure (high altitude > 2700 m) may provide useful insights into the etiology of pathological conditions believed to be associated with placental hypoxia.

Fetal monitoring in type 1 diabetic pregnancies

Stillbirth and perinatal mortality rates are 5 times greater for an insulin-dependant diabetic mother than in the general population. Neonatal and infant mortality rates are 15 and 3 times greater, respectively. In addition, macrosomia is a major problem resulting in both fetal and maternal injury. Fetal monitoring is considered mandatory in such pregnancies. The rational approach would be to use surveillance strategies based on the underlying pathophysiology. However, in the diabetic pregnancy, the underlying pathophysiology is poorly understood and is likely to be multifactorial. Thus, in practice, a pragmatic approach is followed using methods that are applied in other high-risk pregnancies although the pathophysiology is different. Given the limitations in the predictive power of many fetal monitoring methods and the lack of randomised controlled trials, it is not surprising that there is no agreement over the best way to monitor fetal health in diabetic pregnancies. This article analyses the evidence regarding the value of these tests and proposed protocols for their use in the context of the diabetic pregnancy.